Technologies have been developed for manufacturing face inserts for golf club heads. Conventional ways of making golf club heads that include face inserts include providing a club head body having a void or recess into which a face insert is placed, then attaching the face insert to the club head body via adhesive bonding, welding, or another attachment method. The face insert is typically formed by casting, forging, stamping, rolling, etc.
Traditionally, the striking zone of any iron or wedge face includes scoreline grooves, and some type of texturing on the face in between the scorelines to roughen the surface. The purpose of scoreline groove and texture on the striking zone is for the enhancement of ball spin, launch conditions, or performance by increasing the coefficient of friction between the ball cover and face. Conventional ways of making scoreline grooves include casting, forging, CNC milling, engraving, saw cutting, pressing, stamping, etc. Any texture on the face or in between grooves is usually created with a separate operation from the scoreline grooves to increase its surface roughness. Roughening the face surface is conventionally done by blasting (with various media, such as aluminum oxide, glass bead, zirconium bead, steel shot, or the like) or through a milling or fly-cutting machining operation. Microtexturing the face (process of making very fine texture patterns) can be achieved by milling or cutting, scratching, laser etching or chemical etching, or EDM.
Because of the two separate operations, the alignment between scorelines and microtexture features without interference with each other can be a challenge. Also, in order to optimize the performance of a golf club within the 2010 USGA rules, manufacturers seek operations with very tight manufacturing tolerance of scoreline dimensions and surface roughness to be as close as possible to the USGA limit. The tolerance of today's scoreline and roughness dimensions and repeatability of conventional methods often do not facilitate the highest performance requirement. Cutters or spinning tools used in scoreline engraving or fly cutting have limited life (3-7 heads only). Tool wear (even minor wear) can cause scoreline dimensions to be out of spec. Very often, scoreline grooves or microtexture formed do not conform to design specs or the USGA's rules. Creating face texture with milling operations can also lead to circular patterns which aren't consistent across the face, leading to variability in surface roughness at different locations.
The durability of scoreline grooves and microtexture is another challenge. Wearing out of microtexture or damage of scoreline grooves edges after sand bunker shots or thick turf shots is common. These can degrade performance. Although post face hardening processes or coatings, such as QPQ, or nitriding, or surface quenching, or plating, or PVD, can protect or improve durability, it is a challenge to maintain original dimensions and uniform hardness.